This invention relates to improved multi-layered (composite) documents and to apparatus and methods for the manufacture of composite (multi-layered) documents.
There is a growing need and/or desire to have documents which will typically last in excess of five years rather than the typical two years. To produce documents having greater strength and extended durability, the documents are typically formed with multi-layers, which are referred to as “composite” documents. The term “document” as used herein, and in the appended claims, refers to any identification or financial transaction device, including but not limited to national identification (ID) cards, college ID cards, smart cards, driver's licenses, passports, credit cards, documents for holding permanent and long lasting records such as medical records, and all types of security cards. These composite (multi-layered) documents are required to last for a long time even where high temperature levels (hot and cold) and/or a high degree of humidity may be encountered.
Existing problems with, and in, the manufacture of secure and rugged multi-layered documents of extended durability may be explained with reference to FIGS. 1A and 1B, which depict portions of known cards. Typically, these cards include a first core layer (e.g., of Polycarbonate-PC, or polyvinyl chloride-PVC, or polyester terephalate-PET material), 10, having top and bottom surfaces on which information may be printed. Additional layers, 21a, 21b, may be attached to the top and bottoms surfaces, respectively, of the core layer by means of an adhesive strip or coating (210a, 210b). The printed core layer 10 and the layers of adhesive coating (210a, 210b) may be subjected to a platen lamination for bonding all the layers together. However, the adhesive coating prevents a good bond from forming between the layers 21a, 21b and the ink covered core layer. Known conventional adhesives (210a, 210b) used to glue the different layers together have not been satisfactory because the adhesives tend to be moisture sensitive. That is, the exposed edge of each adhesive layer can absorb moisture. As a result, under extended heat or humidity conditions the adhesive bond is weakened and the document layers tend to separate.
A resultant problem with existing multi-layered documents whose layers are glued together is that they can be easily altered. Some of the layers can be removed by putting the documents in a steam chamber and then heating the documents. The layers on the documents can then be peeled off and new counterfeit layers can be mounted on, and added to, the remaining layers of the document. The use of adhesives to attach some of the layers together is problematic, particularly in the manufacture of high security documents, since the adhesives are moisture sensitive and subject to being “peeled”, as noted above, using a steam chamber or like delaminating means. It is therefore desirable and/or necessary that the multi-layered documents not be sensitive to moisture.
Another problem with presently known security documents relates to the use of a layer of laser reactive material attached via an adhesive to a core layer, as shown in FIG. 1B. Typically, a pattern may be printed on at least one of the top and bottom surfaces of the core layer (e.g., a white PC or PVC layer), 10, using “printing” ink. Subsequently laser reactive layers, 12a, 12b, may be attached via adhesive strips 210a, 210b to the printed core layer(s), 10, and a laser may be used to write or print information on and within the laser reactive layer, 12. The laser reactive material tends to heat up when the layer, 12a, 12b, is “written” or “printed”. The heat is transferred to the adhesive coating and the printing ink. This may cause (gas) bubbles to be formed within, and between, the layers by the printing ink and/or by the adhesive, which render the document useless. To prevent over-heating the ink and the adhesive and the destruction of the document, the speed of the laser writing must be slowed. This requires, for example, either the slowing of the scan speed or a reduction in the laser power used to write, whereby multiple passes may be required to print or write data on the document. Doing this substantially increases the time and cost of manufacturing products and still does not result in the production of secure and durable documents.
The problems discussed above are overcome in composite documents formed in accordance with the invention.